The invention relates to an electromagnetic valve, in particular for safety-related pneumatic systems in motor vehicles, with an armature, which, by means of current supplied to an electrical winding, can be displaced axially relative to a core and relative to a first valve seat, inside an inner channel of a coil carrier carrying the winding on a winding section. Furthermore, the invention concerns a safety-related pneumatic system, in particular a pneumatic braking system for motor vehicle applications, in particular for commercial vehicle applications, preferably an ABS or an EBS system.
From DE 93 000 39 U1 an electromagnetic valve is of known art, whose displaceable armature is guided in the course of its axial displacement on the inner periphery of a coil carrier. DE 41 39 670 C2 shows an alternative electromagnetic valve in which such an armature guide is similarly implemented. In addition, the document shows the integral formation of the valve seat with the coil carrier. What is disadvantageous in the electromagnetic valve of known art, however, is the necessarily massive armature, which is responsible for a high weight and high production costs. Moreover, the damping with respect to the core is implemented in a complex manner via a spring pin positioned in the armature. The sealing function with respect to the valve seat is achieved by means of a sealing element that is axially spaced apart from the spring pin.
Preceding designs of electromagnetic valves have not been successfully implemented for safety-related applications, for example for ABS or EBS brake valves in commercial vehicle compressed air brakes, since their functional efficiency is not guaranteed under all conditions of deployment. Thus, in the extreme case, for example as a result of unintentional excess current, the result can be overheating of the winding (coil), as a result of which the coil carrier can reduce its inner diameter, which in forms of embodiment of known art defines the guide clearance for the armature, which brings with it the risk of armature seizure. This can be ascribed to the fact that the winding, which is fitted with an appropriate winding tension, is responsible for the fact that in the event of heating the plastic of the coil carrier does not expand outwards, or only to a limited extent, but rather is forced radially inwards, which leads to the above-referred to problematic reduction of the coil carrier inner diameter.
From DE 10 2005 039 640 A1 an electromagnetic valve for pneumatic systems in motor vehicles is of known art, which has an armature, which, by means of current supplied to an electrical winding, can be displaced axially relative to a core and relative to a first valve seat, inside an inner channel of a coil carrier carrying the winding.
Cited with reference to other prior art that is concerned with electrical valves, are DE 10 2008 042 731 A1, US 2010/0252761 A1, DE 10 2008 060 483 A1, DE 10 2006 055 833 A1, DE 10 2004 001 565 A1, DE 102 53 769 A1, and U.S. Pat. No. 4,341,241 A.